Device (1; 11) according to claim 1, wherein said first resonant circuit element comprises a first antenna element (2) comprising a first coil formation (2') consisting of a series of concentric coils having a first winding direction.

3.

Device (1) according to claim 2, wherein said second resonant circuit element comprises a second antenna element (3) and an integrated circuit (4), said second antenna element (3) being constituted by a second coil formation (3') that are concentric to each other, having a second winding direction opposite said first direction.

4.

Device (1) according to claim 3, wherein said first coil formation {2'), said second coil formation (3') and said integrated circuit (4) are serially connected together electrically by said electric connecting elements (6, 7) , said electric connecting elements (6, 7) comprising a first conductive element (6) and a second conductive element (7) .

5.

Device (11) according to claim 2, wherein said second circuit element comprises an integrated circuit (4) serially connected electrically to said first circuit element by said electric connecting elements (6, I) 1 said electric connecting elements (6, 7) comprising a first conductive element (6) and a second conductive element (7) .

6.

Device (12) according to claim 1, wherein said first resonant circuit element comprises a first antenna element (2) comprising a first coil formation (13) and a second coil formation (13') both constituted by a series of coils that are concentric to one another and have a first winding direction.

7.

Device (12) according to claim 6, wherein said second resonant circuit element comprises a third coil formation (14), a fourth coil formation (14') and an integrated circuit (4) , said third coil formation (14) and said fourth coil formation (14') being both constituted by a series of coils that are concentric to each other and have a second winding direction opposite said first direction.

8.

Device (12) according to claims 6 and 7, wherein said first coil formation (13) is serially connected to said third coil formation (14) , said third coil formation (14) is serially connected to said second coil formation (13'), said second coil formation (13') is serially connected to said fourth coil formation (14') and said integrated circuit (4) is serially connected to said first coil formation (13) and said fourth coil formation (14'), said serial connections being made by said electric connecting elements (6, 7, 6', 7'), said electric connecting elements comprising a first conductive element (6) , a second conductive element (7) a third conductive element (6') and a fourth conductive element (7' ) .

9.

Device (1; 12) according to any one of claims 3, 4, 7, 8, wherein said first antenna element (2) and said second antenna element (3) have a different number of coils.

10.

Device (1, ; 11; 12) according to any preceding claim, wherein said first resonant circuit element (2) is fixed to a first support element (8) , said second resonant circuit element (3, 4; 4) is fixed to a second support element (9) , said first (8) and second (9) support elements being connected together by a connecting element (10) to which said electric connecting elements (6, 7, 6', 7') are connected.

11.

Device according to claim 10, characterised in that it is associable with an object (5) by overlapping between them said first support element (8) and said second support element (9) , so that even said first resonant circuit element (2) and said second resonant circuit element (3, 4; 4) overlap, said first support element (8) and said second support element (9) being fixable together so that it is not possible for them to be separated without interrupting the electrical continuity of said resonant circuit (2, 3, 4; 2, 4) .

Description:

Improved radio-frequency identifying device.

The present invention relates to an improved radio-frequency identifying device, in particular a transponder associable with an object. In the prior-art, associating a radio-frequency identifying device with an object for the purpose of monitoring against thefts, in particular in shops, large stores, etc is known.

The identifying device associated with the object indicates the position thereof and enables it to be realised that the object is being improperly moved, generating for example an alarm signal if the transponder of the identifying device associated with the object leaves the reading field of an appropriate reader.

However, this system of protection against thefts has a considerable drawback, due to the fact that the reader does not actually detect the presence of the object to be monitored but only the presence of the transponder associated with this object.

Therefore, if the transponder is separated from the object with which it is associated and is left in the reader' s reading field, the object can be removed without the monitoring system realising it.

The present invention aims to remedy the above drawback.

According to the present invention, a radio-frequency identifying device is provided that is associable with an object and identifiable by a remote-reading device, said radio-frequency identifying device comprising a resonant circuit, suitable for interacting with said remote-reading device, characterised in that said resonant circuit comprises at least a first circuit element and a second circuit element serially connected electrically to each other and foldable on each other.

One of the two circuit elements comprises an antenna element, whereas the other circuit element comprises at least an integrated circuit connected electrically to the ends of the antenna element.

In an alternative embodiment of the invention one of the two circuit elements comprises a first antenna element, whilst the other circuit element comprises a second antenna element and an integrated circuit, the first and the second antenna element being serially connected together and to said integrated circuit. In this alternative embodiment, the first and the second antenna element are sized in such a way as to be able to interact with the remote reading device only when the first and the second circuit element are folded on each other. In other words, if the first and the second circuit element are not folded on each other, the first and the second antenna element generate two voltages of opposite phases that annul each other, whilst if the first and the second circuit element are folded on each other, which means that the first and the second antenna element overlap each other, the two antenna elements generate two in phase voltages that are added together. The fact that the first and second circuit element are foldable on each other makes it possible to be able to couple the device according to the invention with an object to be protected by overlapping and fixing together the two circuit elements in a permanent manner, in such a way that by removing the device from the object the circuit has necessarily to be interrupted, making it no longer able to interact with the remote-reading device that therefore indicates the separation of the identifying device from the object,, by, for example, activating an alarm signal. This eliminates the possibility that the object can be removed by removing the identifying device therefrom without an alarm signal being activated.

This represents significant progress on the known prior-art identifying devices.

Some purely indicative and non-limitative examples of the invention are illustrated in the following disclosure with reference to the attached drawings, in which:

Figure 1 is a schematic view of a first example of an embodiment of a radio-frequency identifying device according to the invention;

Figures 2 and 3 illustrate the coupling steps with an object to be protected of a radio-frequency identifying device according to the invention;

Figures 4 and 6 illustrate a second example of an embodiment of a device according to the invention; Figure 5 and 7 illustrate a third example of an embodiment of a device according to the invention.

With reference to Figure 1, the device 1 according to the invention comprises a first resonant circuit element constituted by a first antenna element 2 and a second resonant circuit element constituted by a second antenna element 3 and by a microchip 4, serially connected together by a first conductive element 6 and a second conductive element 7. The microchip 4 can, for example, be arranged inside one of the two antenna elements. The two antenna elements 2 and 3 and the microchip 4 are preferably mounted on a pair of support elements 8 and 9 joined together by a bridge 10 on which the conducting elements 6 and 7 (Figures 2 and 3) are arranged. The first antenna element 2 and the second antenna element 3 respectively consist of a first set 2' of coils that are concentric with one another and of a second set 3' of coils that are concentric with one another. The first set 2' of coils and the second set 3' of coils have substantially the same shape and dimensions, but not necessarily the same number of coils, so as to be overlappable. The coils of the first set of coils 2' and the coils of the second set of coils 3' are made in such a way that, in the configuration shown in Figure 1 with the two antenna elements 2, 3 not overlapping and substantially extending over the same plane, the coils of the first set of coils 2' have a winding direction that is contrary to the coils of the second set of coils 3', as indicated by the

arrows Fl and F2, in relation to a magnetic induction flux perpendicular to the plane of the coils.

If, on the other hand, the first set of coils 2' and the second set of coils 3' are overlapped, in the configuration shown in Figure 3, the winding direction of the coils of both sets of coils is the same in relation to a magnetic induction flux perpendicular to the plane of the coils. Figure 2 illustrates the coupling of the device according to the invention with an object to be protected, for example with a ring 5. In order to couple the device with the ring 5, one of the support elements, for example the element 8, is inserted inside the ring, leaving the other element 9 outside. The bridge 10 is then folded back until the two support elements 8 and 9 are overlapped and then the two antenna elements 2' and 3' and the two support elements 8 and 9 are fixed between them in such a way that by separating them it is inevitable that the electrical continuity of the resonant circuit constituted by the two antenna elements 2, 3 and by the microchip 4 is interrupted, making it completely ineffective.

In this way, someone trying to separate the device 1 from the object 5 to be protected cannot avoid interrupting the electrical continuity of said resonant circuit, which means that the remote reader in the field of which the device 1 is located is no longer able to detect the presence the device 1 and thus activates an alarm signal that indicates the absence of a functioning radio-frequency identifying device. This makes it impossible for the object 5 to be protected to be removed without the removal thereof being reported by the remote reader.

Figures 4 and 6 show a second embodiment of a radio- frequency identifying device 11 according to the invention, in a configuration extending over a plane (Figure 4) and in a folded configuration (Figure 6) that the device 11 adopts when it is associated with an object to be protected.

In this second embodiment, the resonant circuit comprises a first circuit element constituted by an antenna element 2 and by a second circuit element constituted by a microchip 4, serially connected to the antenna element 2 by a pair of conductors 6, 7. The antenna element 2 is mounted on a first support element 8 and the microchip 4 is mounted on a second support element 9, connected to the first support element 8 by a bridge 10 on which the conductors 6 and 7 are arranged. The coupling of the device 11 with an object to be protected occurs in the manner disclosed with reference to the first embodiment of the device according to the invention shown in Figures 1 to 3.

Figures 5 and 7 show a third version of a radio-frequency identifying device 12 according to the invention in a configuration extending over a plane (Figure 5) and in a folded configuration (Figure 7) adopted by the device 12 when it is associated with an object to be protected. In this third embodiment, the first resonant circuit element is constituted by a first antenna element 2 comprising a first set of coils 13 and a second set of coils 13' that are concentric with each other; the second resonant circuit element is constituted by a second antenna element 3 comprising a third set of coils 14 and a fourth set of coils 14' that are concentric with one another and a microchip 4. The sets of coils 13, 13, 14, 14' and the microchip 4 are serially connected together electrically by means of a first conducting element 6, a second conducting element 7, a third conducting element 6' and a fourth conducting element 7' . More precisely, the first set of coils 13 is serially connected with the third set of coils 14, the third set of coils 14 is serially connected with the second set of coils 13' , the second set of coils 13' is serially connected with the fourth set of coils 14' and the microchip 4 is serially connected with the fourth set of coils 14' and the first set of coils 13' .

The coils of the first, second, third and fourth set of coils 13, 13', 14, 14' are made in such a way that in the configuration shown in Figure 6 with the two antenna elements 2, 3 not overlapping and substantially extending on the same plane, the coils of the first and second set of coils 13, 13' have a winding direction contrary to the coils of the third and fourth set of coils 14, 14' in relation to a magnetic induction flux that is perpendicular to the plane of the coils. If on the other hand, the first and the second set of coils 13, 13' are superimposed on the third and fourth set of coils 14, 14', in the configuration shown in Figure 7, the winding direction of the coils of all the sets of coils is the same in relation to a magnetic induction flux perpendicular to the plane of the coils. Coupling of the device 12 with an object to be protected occurs in the manner disclosed with reference to the first embodiment of the device according to the invention illustrated in Figures 1 to 3. In the practical embodiment, the materials, dimensions and practical details may be different from those indicated but be technically equivalent to them, without thereby falling outside the scope of legal protection of the present invention.